Flame retardant composition

ABSTRACT

The present invention is a flame-retardant composition comprising a polyolefin polymer, a nano-silicate, a metal hydroxide, and calcium carbonate. The invention also includes a coating prepared from the flame -retardant composition as well as a wire-and-cable construction made by applying the coating over a wire or a cable. The invention also includes articles prepared from the flame-retardant composition, such as extruded sheets, thermoformed sheets, injection-molded articles, coated fabrics, roofing membranes, and wall coverings.

This invention relates to a flame-retardant composition that is usefulfor wire-and-cable applications. This invention also relates towire-and-cable constructions made from the flame-retardant composition.Moreover, the flame retardant composition of this invention is generallyuseful for applications requiring flame retardancy such as extruded orthermoformed sheets, injection-molded articles, coated fabrics,construction (for example, roofing membranes and wall coverings), andautomotive.

Generally, cables must be flame retardant for use in enclosed spaces,such as automobiles, ships, buildings, and industrial plants.Flame-retardant performance of the cable is often achieved by making thecable insulation or outer jacket from a blend of flame-retardantadditives and polymeric materials.

Examples of flame-retardant additives and mechanisms for their use withpolymers are described in Menachem Lewis & Edward D. Weil, Mechanismsand Modes of Action in Flame Retardancy of Polymers, in FIRE RETARDANTMATERIALS 31-68 (A. R. Horrocks & D. Price eds., 2001) and Edward D.Weil, Snergists, Adjuvants, and Antagonists in Flame-Retardant Systems,in FIRE RETARDANCY OF POLYMERIC MATERIALS 115-145 (A. Grand and C. Wilkeeds., 2000).

Flame-retardant additives for use in polyolefin-based compositionsinclude metal hydroxides and halogenated compounds. Useful metalhydroxides include magnesium hydroxide and aluminum trihydroxide, anduseful halogenated compounds include decabromodiphenyloxide.

While flame-retardant additives may operate by one or more mechanisms toinhibit the burning of the polymeric composition made from or containingthe additives, metal hydroxides endothermically liberate water uponheating during combustion. When used in polyolefin-based compositions,metal hydroxides can unfortunately liberate water at elevated processingtemperatures and thereby adversely affect fabrication and extrusion ofinsulating or jacketing layers. Significantly, such release of water canalso cause the composition to foam and thereby result in rough surfacesor voids in the insulation or jacket layer.

Because the quantity of a flame-retardant additive in a polyolefin-basedcomposition can directly affect the composition's flame-retardantperformance, it is often necessary to use high levels of flame retardantadditives in the composition. For example, a wire-and-cable compositionmay contain as much as 65 percent by weight of inorganic fillers or 25percent by weight of halogenated additives. Unfortunately, the use ofhigh levels of flame-retardant additives can be expensive and degradeprocessing of the composition as well as degrade the insulating orjacketing layer's electrical, physical, and mechanical properties.Accordingly, it may be necessary to balance flame retardant performanceagainst cost, processing characteristics, and other properties.

EP 0 370 517 B1, EP 1 052 534 A1, WO 00/52712, WO 00/66657, WO 00/68312,and WO 01/05880 describe the use of various clay and other layeredsilicates to improve the burning characteristics of various polymers.None of these references teaches the replacement of up to 50 percent byweight of a flame-retarding metal hydroxide generally with the inertfiller calcium carbonate. While U.S. Pat. No. 4,826,899 describesreplacing up to 50 percent of alumina trihydrate with calcium carbonatein thermoplastic multi-block copolyester composition, the inventorsrequire that the composition also contain at least 12 percent by weightof magnesium hydroxide and a brominated flame-retardant additive.

A polyolefin-based, flame-retardant composition, having desirableprocessing characteristics and cost advantages over conventionalcompositions while retaining desirable flame retardant performance, isneeded. More specifically, a polyolefin-based, flame-retardant-cablecomposition, having calcium carbonate present in amount up to the totalamount of metal hydroxide components, is needed.

The present invention is a flame-retardant composition comprising apolyolefin polymer, a nano-silicate, a metal hydroxide, and calciumcarbonate. The invention also includes a coating prepared from theflame-retardant composition as well as a wire-and-cable constructionmade by applying the coating over a wire or a cable. The invention alsoincludes articles prepared from the flame-retardant composition, such asextruded sheets, thermoformed sheets, injection-molded articles, coatedfabrics, roofing membranes, and wall coverings.

Suitable wire-and-cable constructions, which may be made by applying thecoating over a wire or a cable, include: (a) insulation and jacketingfor copper telephone cable, coaxial cable, and medium and low voltagepower cable and (b) fiber optic buffer and core tubes. Other examples ofsuitable wire-and-cable constructions are described in ELECTRIC WIREHANDBOOK (J. Gillett & M. Suba, eds., 1983) and POWER AND COMMUNICATIONCABLES THEORY AND APPLICATIONS (R. Baitnikas & K Srivastava eds., 2000).Moreover, additional examples of suitable wire-and-cable constructionswould be readily apparent to persons of ordinary skill in the art. Anyof these constructions can be advantageously coated with a compositionof the present invention.

The invented flame-retardant composition comprises a polyolefin polymerand effective amounts of a nano-silicate, a metal hydroxide, and calciumcarbonate. Suitable polyolefin polymers include ethylene polymers,propylene polymers, and blends thereof.

Ethylene polymer, as that term is used herein, is a homopolymer ofethylene or a copolymer of ethylene and a minor proportion of one ormore alpha-olefins having 3 to 12 carbon atoms, and preferably 4 to 8carbon atoms, and, optionally, a diene, or a mixture or blend of suchhomopolymers and copolymers. The mixture can be a mechanical blend or anin situ blend. Examples of the alpha-olefins are propylene, 1-butene,1-hexene, 4-methyl-1-pentene, and 1-octene. The polyethylene can also bea copolymer of ethylene and an unsaturated ester such as a vinyl ester(for example, vinyl acetate or an acrylic or methacrylic acid ester), acopolymer of ethylene and an unsaturated acid such as acrylic acid, or acopolymer of ethylene and a vinyl silane (for example,vinyltrimethoxysilane and vinyltriethoxysilane).

The polyethylene can be homogeneous or heterogeneous. The homogeneouspolyethylenes usually have a polydispersity (Mw/Mn) in the range of 1.5to 3.5 and an essentially uniform comonomer distribution, and arecharacterized by a single and relatively low melting point as measuredby a differential scanning calorimeter. The heterogeneous polyethylenesusually have a polydispersity (Mw/Mn) greater than 3.5 and lack auniform comonomer distribution. Mw is defined as weight averagemolecular weight, and Mn is defined as number average molecular weight.

The polyethylenes can have a density in the range of 0.860 to 0.960 gramper cubic centimeter, and preferably have a density in the range of0.870 to 0.955 gram per cubic centimeter. They also can have a meltindex in the range of 0.1 to 50 grams per 10 minutes. If thepolyethylene is a homopolymer, its melt index is preferably in the rangeof 0.75 to 3 grams per 10 minutes. Melt index is determined under ASTMD-1238, Condition E and measured at 190 degree C and 2160 grams.

Low- or high-pressure processes can produce the polyethylenes. They canbe produced in gas phase processes or in liquid phase processes (thatis, solution or slurry processes) by conventional techniques.Low-pressure processes are typically run at pressures below 1000 poundsper square inch (“psi”) whereas high-pressure processes are typicallyrun at pressures above 15,000 psi.

Typical catalyst systems for preparing these polyethylenes includemagnesium/titanium-based catalyst systems, vanadium-based catalystsystems, chromium-based catalyst systems, metallocene catalyst systems,and other transition metal catalyst systems. Many of these catalystsystems are often referred to as Ziegler-Natta catalyst systems orPhillips catalyst systems. Useful catalyst systems include catalystsusing chromium or molybdenum oxides on silica-alumina supports.

Useful polyethylenes include low density homopolymers of ethylene madeby high pressure processes (HP-LDPEs), linear low density polyethylenes(LLDPEs), very low density polyethylenes (VLDPEs), ultra low densitypolyethylenes (ULDPEs), medium density polyethylenes (MDPEs), highdensity polyethylene (HDPE), and metallocene copolymers.

High-pressure processes are typically free radical initiatedpolymerizations and conducted in a tubular reactor or a stirredautoclave. In the tubular reactor, the pressure is within the range of25,000 to 45,000 psi and the temperature is in the range of 200 to 350degree C. In the stirred autoclave, the pressure is in the range of10,000 to 30,000 psi and the temperature is in the range of 175 to 250degree C.

Copolymers comprised of ethylene and unsaturated esters or acids arewell known and can be prepared by conventional high-pressure techniques.The unsaturated esters can be alkyl acrylates, alkyl methacrylates, orvinyl carboxylates. The alkyl groups can have 1 to 8 carbon atoms andpreferably have 1 to 4 carbon atoms. The carboxylate groups can have 2to 8 carbon atoms and preferably have 2 to 5 carbon atoms. The portionof the copolymer attributed to the ester comonomer can be in the rangeof 5 to 50 percent by weight based on the weight of the copolymer, andis preferably in the range of 15 to 40 percent by weight. Examples ofthe acrylates and methacrylates are ethyl acrylate, methyl acrylate,methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butylmethacrylate, and 2-ethylhexyl acrylate. Examples of the vinylcarboxylates are vinyl acetate, vinyl propionate, and vinyl butanoate.Examples of the unsaturated acids include acrylic acids or maleic acids.

The melt index of the ethylene/unsaturated ester copolymers orethylene/unsaturated acid copolymers can be in the range of 0.5 to 50grams per 10 minutes, and is preferably in the range of 2 to 25 gramsper 10 minutes.

Copolymers of ethylene and vinyl silanes may also be used. Examples ofsuitable silanes are vinyltrimethoxysilane and vinyltriethoxysilane.Such polymers are typically made using a high-pressure process. Use ofsuch ethylene vinylsilane copolymers is desirable when a moisturecrosslinkable composition is desired. Optionally, a moisturecrosslinkable composition can be obtained by using a polyethylenegrafted with a vinylsilane in the presence of a free radical initiator.When a silane-containing polyethylene is used, it may also be desirableto include a crosslinking catalyst in the formulation (such asdibutyltindilaurate or dodecylbenzenesulfonic acid) or another Lewis orBronsted acid or base catalyst.

The VLDPE or ULDPE can be a copolymer of ethylene and one or morealpha-olefins having 3 to 12 carbon atoms and preferably 3 to 8 carbonatoms. The density of the VLDPE or ULDPE can be in the range of 0.870 to0.915 gram per cubic centimeter. The melt index of the VLDPE or ULDPEcan be in the range of 0.1 to 20 grams per 10 minutes and is preferablyin the range of 0.3 to 5 grams per 10 minutes. The portion of the VLDPEor ULDPE attributed to the comonomer(s), other than ethylene, can be inthe range of 1 to 49 percent by weight based on the weight of thecopolymer and is preferably in the range of 15 to 40 percent by weight.

A third comonomer can be included, for example, another alpha-olefin ora diene such as ethylidene norbornene, butadiene, 1,4-hexadiene, or adicyclopentadiene. Ethylene/propylene copolymers are generally referredto as EPRs and ethylene/propylene/diene terpolymers are generallyreferred to as an EPDM. The third comonomer can be present in an amountof 1 to 15 percent by weight based on the weight of the copolymer and ispreferably present in an amount of 1 to 10 percent by weight. It ispreferred that the copolymer contains two or three comonomers inclusiveof ethylene.

The LLDPE can include VLDPE, ULDPE, and MDPE, which are also linear,but, generally, has a density in the range of 0.916 to 0.925 gram percubic centimeter. It can be a copolymer of ethylene and one or morealpha-olefins having 3 to 12 carbon atoms, and preferably 3 to 8 carbonatoms. The melt index can be in the range of 1 to 20 grams per 10minutes, and is preferably in the range of 3 to 8 grams per 10 minutes.

Any polypropylene may be used in these compositions. Examples includehomopolymers of propylene, copolymers of propylene and other olefins,and terpolymers of propylene, ethylene, and dienes (for example,norbomadiene and decadiene). Additionally, the polypropylenes may bedispersed or blended with other polymers such as EPR or EPDM. Examplesof polypropylenes are described in POLYPROPYLENE HANDBOOK:POLYMERIZATION, CHARACTERIZATION, PROPERTIES, PROCESSING, APPLICATIONS3-14, 113-176 (E. Moore, Jr. ed., 1996).

Suitable polypropylenes may be components of TPEs, TPOs and TPVs. Thosepolypropylene-containing TPEs, TPOs, and TPVs can be used in thisapplication.

The nano-silicate has at least one dimension in the 0.9 to 200nanometer-size range, preferably 0.9 to 150 nanometers, more preferably0.9 to 100 nanometers, and most preferably 0.9 to 30 nanometers. Thenano-silicates are effective in the composition at a concentration of0.1 percent to 15 percent by weight, based on the total formulation.

Preferably, the nano-silicates are layered, including nano-silicatessuch as montmorillonite, magadiite, fluorinated synthetic mica,saponite, fluorhectorite, laponite, sepiolite, attapulgite, hectorite,beidellite, vermiculite, kaolinite, nontronite, volkonskoite,stevensite, pyrosite, sauconite, and kenyaite. In the more preferredembodiment, the layered nano-silicates of the present invention aremontmorillonite or magadiite. The layered nano-silicates may benaturally occurring or synthetic.

Some of the cations (for example, sodium ions) of the nano-silicate canbe exchanged with an organic cation, by treating the nano-silicate withan organic cation-containing compound. Alternatively, the cation caninclude or be replaced with a hydrogen ion (proton). For wire and cablecompositions, preferred exchange cations are imidazolium, phosphonium,ammonium, alkyl ammonium, and polyalkyl ammonium. An example of asuitable ammonium compound is dimethyl, di(hydrogenated tallow)ammonium. Preferably, the cationic coating will be present in 15 to 50percent by weight, based on the total weight of layered nano-silicateplus cationic coating. In the most preferred embodiment, the cationiccoating will be present at greater than 30 percent by weight, based onthe total weight of layered nano-silicate plus cationic coating. Anotherpreferred ammonium coating is octadecyl ammonium.

The composition may contain a coupling agent to improve thecompatibility between the polyolefin polymer and the nano-silicate.Examples of coupling agents include silanes, titanates, zirconates, andvarious polymers grafted with maleic anhydride. Other couplingtechnology would be readily apparent to persons of ordinary skill in theart and is considered within the scope of this invention.

Suitable metal hydroxide compounds include aluminum trihydroxide (alsoknown as ATH or aluminum trihydrate) and magnesium hydroxide (also knownas magnesium dihydroxide). Other flame-retarding metal hydroxides areknown to persons of ordinary skill in the art. The use of those metalhydroxides is considered within the scope of the present invention.

Calcium carbonate is also well known in the art.

The surface of the metal hydroxide and/or the calcium carbonate may becoated with one or more materials, including silanes, titanates,zirconates, carboxylic acids, and maleic anhydride-grafted polymers.Suitable coatings include those disclosed in U.S. Pat. No. 6,500,882.The average particle size may range from less than 0.1 micrometers to 50micrometers. In some cases, it may be desirable to use a metal hydroxideand/or calcium carbonate having a nano-scale particle size. The metalhydroxide and/or the calcium carbonate may be naturally occurring orsynthetic.

The flame-retardant composition may contain other flame-retardantadditives. Other suitable non-halogenated flame retardant additivesinclude red phosphorus, silica, alumina, titanium oxides, talc, clay,organo-modified clay, zinc borate, antimony trioxide, wollastonite,mica, silicone polymers, phosphate esters, hindered amine stabilizers,ammonium octamolybdate, intumescent compounds, and expandable graphite.Suitable halogenated flame retardant additives include decabromodiphenyloxide, decabromodiphenyl ethane, ethylene-bis (tetrabromophthalimide),and dechlorane plus.

In addition, the composition may contain other additives such asantioxidants, stabilizers, blowing agents, carbon black, pigments,processing aids, peroxides, cure boosters, and surface active agents totreat fillers may be present. Furthermore, the composition may bethermoplastic or crosslinked.

In a preferred embodiment, the flame-retardant composition comprises:(a) a polyolefin polymer selected from the group consisting of ethylenepolymers and propylene polymers; (b) a layered nano-silicate selectedfrom the group consisting of montmorillonite and magadiite; (c) a metalhydroxide selected from the group consisting of aluminum trihydroxideand magnesium hydroxide; and (d) calcium carbonate.

In another embodiment of the present invention, the invention is acoating prepared from the flame-retardant composition.

In yet another embodiment of the present invention, a variety of methodsfor preparing suitable wire-and-cable constructions are contemplated andwould be readily apparent to persons of ordinary skill in the art. Forexample, conventional extrusion processes may be used to prepare aflame-retardant wire or cable construction by applying theflame-retardant composition as a coating over a wire or a cable.

In another embodiment of the present invention, the invention is anarticle prepared from the flame-retardant composition, where the articleis selected from the group consisting of extruded sheets, thermoformedsheets, injection-molded articles, coated fabrics, roofing membranes,and wall coverings. For these applications, it is contemplated that theflame-retardant composition may be used to prepare articles in a varietyof processes including extrusion, thermoforming, injection molded,calendering, and blow molding as well as other processes readilyapparent to persons of ordinary skill in the art.

EXAMPLES

The following non-limiting examples illustrate the invention.

Example 1 The Nano-Silicate Masterbatch

A montruorillonite in ethylene vinylacetate copolymer masterbatch wasprepared using a Brabender™ mixer equipped with a 250-ml mixing bowl.The mixer was set to a mixing temperature of 120 degrees C. and mixingrate of 100 RPM. The mixer was initially charged with DuPont Elvax 265™ethylene vinylacetate copolymer (“EVA-1”) and Irganox 1010FF™ tetrakis[methylene (3,5-di-tert-butyl-4-hydroxyhydro-cinnamate)]methane. Theethylene vinylacetate copolymer contained 28 percent vinyl acetate byweight and had a melt index of 3 grams/10 min. After the mixture wasfully melted, the mixer was then charged with Nanomer I.30P™montmorillonite clay, having been treated with 30 percent by weight ofoctadecylammonium and available from Nanocor, Inc.

The three components were added at a weight ratio of 49.80:50.00:0.20 ofEVA-1:montmorillonite:Irganox 1010FF™ tetrakis [methylene(3,5-di-tert-butyl-4-hydroxyhydro-cinnamate)]methane. After thecomponents were added, the mixing time was continued for 15 minutes.

Examples 2-44 The Comparative Specimens

For preparing Examples 2-44, a Brabender™ mixer equipped with a 250-mlmixing bowl was also used. The mixer was set to a mixing temperature of110 degrees C. and mixing rate of 80 RPM.

The mixer was initially charged with an ethylene vinylacetate copolymerand 0.20 percent by weight of Irganox 1100FF™ tetrakis [methylene(3,5-di-tert-butyl-4-hydroxyhydro-cinnamate)]methane. The ethylenevinylacetate copolymer used was dupont Elvax 260™ ethylene vinylacetate(“EVA-2”), which contained 28 percent vinyl acetate by weight and had amelt index of 6 grams/10 min.

After the EVA-2 mixture was fully melted, the remaining components weresequentially added in the proportions shown: (1) the nano-silicatemasterbatch; (2) the metal hydroxide; (3) the calcium carbonate; and (4)10 percent by weight of maleic anhydride grafted polyethylene. Mixingwas then continued for 15 minutes.

When the metal hydroxide was magnesium hydroxide, the metal hydroxidehad a surface area of 6.1 m²/g, as determined by the BET method, and anaverage particle size of 0.8 microns (800 nanometers) and was surfacetreated with 0.1 percent by weight of oleic acid. When the metalhydroxide was aluminum trihydroxide, the metal hydroxide had a surfacearea of 5.2 m²/g, as determined by the BET method, and an averageparticle size of 1.1 microns (1100 nanometers).

The calcium carbonate was ground and had a surface area of 3 m²/g, asdetermined by the BET method, and an average particle size of 3.5microns (3500 nanometers). The maleic anhydride grafted polyethylene wasa linear low density ethylene-hexene copolymer grafted with 0.3 percentby weight of maleic anhydride and having melt index of 3.2 grams/10minutes and a density of 0.917 grams/cc.

Examples 2-44 yielded compositions having the nano-silicate, the metalhydroxide, and the calcium carbonate components together constituting 35percent, 50 percent, or 65 percent by weight of the total composition.

The compositions were then removed from the mixer and prepared in totest specimens suitable for testing in the UL-94 Vertical Flame Test.The test results are provided in Tables I-III.

In the UL-94 test, a flame is applied to a test specimen twice and theduration of burning after each flame application is noted. A shortertime represents better performance. An UL-94 rating of V0 is the bestrating possible and indicates that a material self extinguishes quicklywithout releasing flaming drops while burning.

The test specimens had a thickness of 125 mil. The burn time is listedin seconds for each specimen for the first and second flame applicationand separated by a slash. If the table does not show a slash, a secondflame application was not applied. The total flaming combustion time isthe sum of the first and second burn times for all five samples, exceptwhen less than five samples were burned. When less than five sampleswere burned, the total flaming combustion time is the sum of the firstand second burn times for all samples burned.

A. 35 Percent Test Specimens

Examples 2-7 and 8-16 represent 35 percent by weight componentcompositions. None of the test specimens prepared from the 35 percentcomposition achieved a V0 rating.

B. 50 Percent Test Specimens

Examples 17-21 and 22-29 represent 50 percent by weight componentcompositions. None of the test specimens prepared from the 50 percentcomposition achieved a V0 rating.

C. 65 Percent Test Specimens

Examples 30-35 and 36-44 represent 65 percent by weight componentcompositions. Test specimens prepared from a composition having theflame-retardant additive mixture comprised of only a metal hydroxide at65 percent by weight achieved a V0 rating as illustrated by Examples 35and 44. The test specimen prepared from a composition having the flameretardant additive mixture comprised of only calcium carbonate at 65percent by weight failed to achieve a V0 rating as illustrated byExample 42.

Test specimens prepared from a composition having a two-component flameretardant additive mixture comprised of a metal hydroxide at 62 percentby weight and the nano-silicate at 3 percent by weight also achieved aV0 rating as illustrated by Examples 33 and 41. Test specimens preparedfrom a composition having a two-component flame retardant additivemixture comprised of a metal hydroxide at 59 percent by weight and thenano-silicate at 6 percent by weight also achieved a V0 rating asillustrated by Examples 31 and 38.

Test specimens prepared from a composition having a two-component flameretardant additive mixture comprised of calcium carbonate at 62 percentby weight and the nano-silicate at 3 percent by weight failed toachieved a V0 rating as illustrated by Example 39. Test specimensprepared from a composition having a two-component flame retardantadditive mixture comprised of calcium carbonate at 59 percent by weightand the nano-silicate at 6 percent by weight also failed to achieve a V0rating as illustrated by Examples 36.

Test specimens prepared from a composition having a two-component flameretardant additive mixture comprised of a metal hydroxide at 32.5percent by weight and calcium carbonate at 32.5 percent by weight failedto achieved a V0 rating as illustrated by Examples 34 and 43.

Surprisingly, test specimens achieved V0 ratings when prepared from acomposition having a three-component flame retardant additive at thefollowing additive levels: (a) 29.5 percent by weight of metalhydroxide, 29.5 percent by weight of calcium carbonate, and 6 percent byweight of the nano-silicate, as illustrated by Examples 30 and 37 and(b) 31 percent by weight of metal hydroxide, 31 percent by weight ofcalcium carbonate, and 3 percent by weight of the nano-silicate, asillustrated by Examples 32 and 40. TABLE I Example 2 3 4 5 6 7 8 9 EVA-248.80 48.80 51.80 51.80 54.80 54.80 48.80 48.80 Magnesium hydroxide14.50 29.00 16.00 32.00 17.50 35.00 Aluminum trihydroxide 0.00 14.50Calcium carbonate 14.50 16.00 17.50 0.00 29.00 14.50 50 percentNano-silicate 12.00 12.00 6.00 6.00 0.00 0.00 12.00 12.00 MasterbatchUL-94 Vertical Flaming Test Flaming Duration Test Specimen 1 394 12/346242 331 181 0/233 200+/ 300+/ NA NA Test Specimen 2 399 3/351 217 324213 0/213 200+/ 200+/ NA NA Test Specimen 3 374 4/337 233 348 204 0/238Test Specimen 4 388 8/345 251 350 190 0/249 Test Specimen 5 402 359 237327 183 0/222 Total Flaming Combustion Time 1,957 1.765 1,180 1,680 9711,160 >400 >500 (sec) Ignite Cotton No Yes Yes Yes Yes Yes No NoClassification None None None None None None None None Example 10 11 1213 14 15 16 EVA-2 48.80 51.80 51.80 51.80 54.80 54.80 54.80 Magnesiumhydroxide Aluminum trihydroxide 29.00 0.00 16.00 32.00 0.00 17.50 35.00Calcium carbonate 0.00 32.00 16.00 0.00 35.00 17.50 0.00 50 percentNano-silicate 12.00 6.00 6.00 6.00 0.00 0.00 0.00 Masterbatch UL-94Vertical Flaming Test Flaming Duration Test Specimen 1 200+/ 100+/ 100+/100+/ 100+/ 100+/ 0/100+ NA NA NA NA NA NA Test Specimen 2 200+/ 100+/100+/ 100+/ 100+/ 43/ 0/15 NA NA NA NA NA 100+ Test Specimen 3 0/32 TestSpecimen 4 0/40 Test Specimen 5 0/32 Total Flaming CombustionTime >400 >200 >200 >200 >200 >243 >219 (sec) Ignite Cotton No Yes YesYes Yes No Yes Classification None None None None None None None

TABLE II Example 17 18 19 20 21 22 23 EVA-2 33.80 33.80 36.80 39.8039.80 33.80 33.80 Magnesium hydroxide 22.00 44.00 47.00 25.00 50.00Aluminum trihydroxide 0.00 22.00 Calcium carbonate 22.00 0.00 0.00 25.000.00 44.00 22.00 50 percent Nano-silicate 12.00 12.00 6.00 0.00 0.0012.00 12.00 Masterbatch UL-94 Vertical Flaming Test Flaming DurationTest Specimen 1 0/555 0/9 0/89 214 0/39  200+/NA 188/0 Test Specimen 20/541 0/6 0/22 188 0/288 200+/NA 166/0 Test Specimen 3 0/549  0/36 0/11197 0/38    56/200+ Test Specimen 4 0/521 0/4 0/8  223 0/269    4/200+Test Specimen 5 0/538 0/0 0/41 199 0/294 312/0 Total Flaming CombustionTime 2,704 55 171 1,021 928 >400 >1126 (sec) Ignite Cotton No No No YesYes No No Classification None None None None None None None Example 2425 26 27 28 29 EVA-2 33.80 36.80 36.80 39.80 39.80 39.80 Magnesiumhydroxide Aluminum trihydroxide 44.00 0.00 47.00 0.00 25.00 50.00Calcium carbonate 0.00 47.00 0.00 50.00 25.00 0.00 50 percentNano-silicate 12.00 6.00 6.00 0.00 0.00 0.00 Masterbatch UL-94 VerticalFlaming Test Flaming Duration Test Specimen 1 2/24 200+/ 0/54 100+/0/100+ 0/0 NA NA Test Specimen 2 2/19 200+/ 0/52 100+/ 0/100+   0/100+NA NA Test Specimen 3 3/21 0/54 0/0 Test Specimen 4 1/32 0/1  0/0 TestSpecimen 5 0/32 0/4  0/0 Total Flaming Combustion Time 136 >400165 >200 >200 >100 (sec) Ignite Cotton No Yes No Yes Yes YesClassification None None None None None None

TABLE III Example 30 31 32 33 34 35 36 37 EVA-2 18.80 18.80 21.80 21.8024.80 24.80 18.80 18.80 Magnesium hydroxide 29.50 59.00 31.00 62.0032.50 65.00 Aluminum trihydroxide 0.00 29.50 Calcium carbonate 29.500.00 31.00 0.00 32.50 0.00 59.00 29.50 50 percent Nano-silicate 12.0012.00 6.00 6.00 0.00 0.00 12.00 12.00 Masterbatch UL-94 Vertical FlamingTest Flaming Duration Test Specimen 1 0/0 0/1 0/3 0/0 0/13 0/0 200+/ 0/0NA Test Specimen 2 0/2 0/2 0/0 0/0 0/15 0/0 200+/ 0/0 NA Test Specimen 30/0 0/0 0/0 0/0 0/29 0/0 0/0 Test Specimen 4 0/1 0/0 0/0 0/0 0/12 0/00/0 Test Specimen 5 0/0 0/0 0/0 0/0 0/51 0/0 0/1 Total FlamingCombustion Time 3 3 3 0 120 0 >400 1 (sec) Ignite Cotton No No No No NoNo No No Classification V-0 V-0 V-0 V-0 None V-0 None V-0 Example 38 3940 41 42 43 44 EVA-2 18.80 21.80 21.80 21.80 24.80 24.80 24.80 Magnesiumhydroxide Aluminum trihydroxide 59.00 0.00 31.00 62.00 0.00 32.50 65.00Calcium carbonate 0.00 62.00 31.00 0.00 65.00 32.50 0.00 50 percentNano-silicate 12.00 6.00 6.00 6.00 0.00 0.00 0.00 Masterbatch UL-94Vertical Flaming Test Flaming Duration Test Specimen 1 0/0 200+/ 0/2 0/0100+/ 0/75 0/0 NA NA Test Specimen 2 0/0 200+/ 0/0 0/0 100+/ 1/43 0/0 NANA Test Specimen 3 0/0 0/0 0/0 0/21 0/0 Test Specimen 4 0/0 0/0 0/0 0/790/0 Test Specimen 5 0/0 0/0 0/0 0/83 0/0 Total Flaming Combustion Time0 >400 2 0 >200 >302 0 (sec) Ignite Cotton No Yes No No Yes Yes NoClassification V-0 None V-0 V-0 None None V-0

1. A flame retardant composition comprising: a. a polyolefin polymer; b.a nano-silicate; c. a metal hydroxide; and d. calcium carbonate.
 2. Theflame-retardant composition of claim 1 wherein the polyolefin polymer isselected from the group consisting of ethylene polymers and propylenepolymers.
 3. The flame-retardant composition of claim 1 wherein thenano-silicate is a layered nano-silicate.
 4. The flame-retardantcomposition of claim 3 wherein the nano-silicate is present in an amountbetween 0.1 percent and 15 percent by weight.
 5. The flame retardantcomposition of claim 3 wherein the nano-silicate is selected from thegroup consisting of montmorillonite, magadiite, fluorinated syntheticmica, saponite, fluorhectorite, laponite, sepiolite, attapulgite,hectorite, beidellite, vermiculite, kaolinite, nontronite, volkonskoite,stevensite, pyrosite, sauconite, and kenyaite.
 6. The flame-retardantcomposition of claim 5 wherein the nano-silicate is selected from thegroup consisting of montmorillonite and magadiite.
 7. Theflame-retardant composition of claim 3 wherein the nano-silicate istreated with an organic cation.
 8. The flame-retardant composition ofclaim 7 wherein the organic cation is selected from the group consistingof imidazolium, phosphonium, ammonium, alkyl ammonium, and polyalkylammonium.
 9. The flame-retardant composition of claim 1 wherein themetal hydroxide is selected from the group consisting of aluminumtrihydroxide and magnesium hydroxide.
 10. The flame retardantcomposition of claim 1 wherein the surface of the metal hydroxide iscoated with a material selected from the group consisting of silanes,titanates, zirconates, carboxylic acids, and maleic anhydride-graftedpolymers.
 11. The flame retardant composition of claim 1 wherein thesurface of the calcium carbonate is coated with a material selected fromthe group consisting of silanes, titanates, zirconates, carboxylicacids, and maleic anhydride-grafted polymers.
 12. A coating preparedfrom the flame-retardant composition of claim
 1. 13. A flame-retardantwire or cable construction prepared by applying the coating of claim 12over a wire or cable.
 14. An article prepared from the flame-retardantcomposition of claim 1, where the article is selected from the groupconsisting of extruded sheets, thermoformed sheets, injection-moldedarticles, coated fabrics, roofing membranes, and wall coverings.
 15. Aflame retardant composition comprising: a. a polyolefin polymer selectedfrom the group consisting of ethylene polymers and propylene polymers;b. a layered nano-silicate selected from the group consisting ofmontmorillonite and magadiite; c. a metal hydroxide selected from thegroup consisting of aluminum trihydroxide and magnesium hydroxide; andd. calcium carbonate.
 16. A coating prepared from the flame-retardantcomposition of claim
 15. 17. A flame-retardant wire or cableconstruction prepared by applying the coating of claim 16 over a wire orcable.
 18. An article prepared from the flame-retardant composition ofclaim 15, where the article is selected from the group consisting ofextruded sheets, thermoformed sheets, injection-molded articles, coatedfabrics, roofing membranes, and wall coverings.